1. Field of the Invention
The present invention generally relates to lighted footwear and, more particularly, to a motion responsive switch for use in creating an attractive lighting pattern.
2. Description of the Related Art
Lighted footwear is popular with children and adults, not only for its safety aspect in which illuminated lights on the footwear render the wearer more visible especially at night, but also for its aesthetic appeal. Such lighted footwear typically includes at least one light source and preferably a plurality of light sources such as light emitting diodes (LEDs), a source of power preferably a battery, and a switch to connect the battery to the LEDs and cause the latter to light.
The switch can be a simple manual switch as disclosed, for example, in U.S. Pat. No. 4,158,922. The switch could be a mercury switch in which a ball of mercury runs back and forth along a tube between a pair of electrical contacts during motion of the footwear, as disclosed in U.S. Pat. No. 4,848,009. The switch can be a pressure responsive switch which opens and closes in response to application of the wearer""s weight on the switch as disclosed, for example, in U.S. Pat. No. 5,285,586. The switch can be a spring switch in which a cantilevered spring in the form of a coil oscillates back and forth to make and break contact with an electrical contact as, for example, shown in U.S. Pat. No. 5,408,764. The switch may include a metal ball that moves when the footwear moves. Thus, as shown in U.S. Pat. No. 2,572,760, a ball rolls back and forth along a tube pivotably mounted on a shoe to tilt the tube and cause a light to flash. U.S. Pat. No. 5,438,493 discloses a ball that moves along a sliding way to control operation of a switch. U.S. Pat. No. 5,483,759 discloses a ball that rolls across multiple contacts during walking or running.
To increase battery life and to provide a more attractive eye-catching and safer display, it is desirable to cause the light to flash on and off, rather than being maintained continuously illuminated while the switch is closed. This can be accomplished mechanically by the back and forth movement of the above-described mercury or metal balls, or by the oscillation of the aforementioned coil spring, or by the intermittent application of weight in a pressure responsive switch.
Another way to cause flashing is electronically by use of an oscillator or flasher, preferably at low speeds on the order of a few Hertz, as for example described in U.S. Pat. No. 4,158,922. The switch is then used not to make intermittent contact, but instead, a switch closure is employed to trigger an electronic component such as an integrated circuit to initiate a flashing light sequence.
As advantageous as these known switches have been, experience has shown that there are still drawbacks in their use. Mercury switches are no longer used for environmental reasons. Metal balls do not always make a reliable electrical contact. Pressure responsive switches, as well as the aforementioned mercury and metal ball rolling switches, can, under certain circumstances, remain continuously closed, thus allowing the lights to stay on until eventually the battery is exhausted. For example, during transport, shoes with such switches can be packed at an attitude corresponding to a step during walking or running, or can be tightly packed together with sufficient pressure to maintain the lights on and exhaust the battery.
Accordingly, it is a general object of this invention to improve the state of the art of motion responsive switches used in lighted footwear.
More particularly, it is an object of the present invention to provide an inertial switch that makes a reliable electrical connection during use.
In keeping with the above objects and others which will become apparent hereafter, one feature of the present invention resides, briefly stated, in an inertial switch mounted together with a battery and at least one light on footwear for joint movement therewith. The switch includes a housing having walls bounding an interior. The walls include upper and lower walls spaced apart along an upright longitudinal axis, as well as side walls spaced apart along a transverse axis generally perpendicular to the longitudinal axis. In one embodiment, the housing is a circular cylinder, and the upper and lower wells lie in parallel planes perpendicular to the longitudinal axis. The side walls extend circumferentially around the longitudinal axis. In another embodiment, the housing is a hollow sphere.
The switch includes a pair of upper and lower electrical terminals respectively mounted on the upper and lower walls. The terminals are spaced apart by a first distance along the longitudinal axis. The terminals are spaced from the side walls by a second distance along the transverse axis.
An electrically conductive rolling ball is mounted in the interior of the housing for rolling with multiple freedoms of movement. The ball has a diameter greater than the first distance and less than the second distance. The ball is free to roll between a non-contacting position in which the ball is spaced away from the terminals, and a contacting position in which the ball contacts the terminals and electrically connects the battery and the light to illuminate the light.
In the preferred embodiment, the longitudinal axis extends centrally of the housing, and the housing is symmetrical relative to the longitudinal axis. The terminals are preferably configured as circular plates whose centers lie on the longitudinal axis.
In use, the ball rolls in many directions, including around the longitudinal axis as the footwear is moved. When the ball moves radially toward the longitudinal axis, the ball engages both terminals simultaneously due to its greater diameter and effectively allows an electrical current to pass through the ball between the terminals. When the ball moves radially outwardly away from the terminals toward the side walls, there is sufficient room in the housing for the ball to be spaced out of contact with the terminals. The switch therefore closes when the ball engages the terminals, and opens when the ball is disengaged from the terminals.
The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.